Please note: I no longer recommend stuffing of the ear cups with Fiberloft and have not for some time (stuffing pads is still strongly recommended). If you are intent on trying it, please be prepared to remove it when you discover the effect is not always positive in all areas.

About This Mod
This mod is the result of a painstaking (and painful!) process I started some time ago, trying to get the stock Denon AH-D5000 headphone to sound right. I have gone through 4 separate D5000s, and dozens of iterations of this mod, using different materials, techniques, and strategies, carefully A/B-ing one Denon against a more evolved version, to test the before and after results of each progressive step and new tweak employed. If it didn't work, I threw it out. If it worked, I kept it and moved on.

I am confident that most audiophiles and headphone fanatics will find the result of these modifications to the Denon D5000 quite surprising, especially if you bother to spend any time with the stock version. The stock D5000, though generally admired as a good enough headphone at its price point, is IMHO, a seriously flawed product (more on this shortly); but I heard enough promising aspects to try to see if I could "rescue" them.

And, man, am I glad I did! Properly tweaked, this is the finest dynamic headphone I've heard to date (and I've owned almost all of the contenders). In fact, I liked them so much, I sold my beloved Sony MDR-R10 headphones ($4K list, scarce, legendary, lusted after, and now extinct) in favor of keeping the modified Denons. For Head-Fiers who go back a ways and are familiar with my posts, many found that hard to believe, knowing how much I deeply loved them Sonys.

After mod-ing the D5000, I found only a few small areas in which the R10 came out ahead. But in all the fundamentals, I could not deny that the Denons were a significant upgrade. And at approximately 1/8th the price!

What Is Wrong With The Stock AH-D5000?
Initially, when I got the Denon D5000, I was pretty disappointed with it. As has been well documented, it has this flabby almost flatulent bass response that can sound like a giant farting sound or like a woopie cushion deflating into your eardrum. The bass response is nothing short of obnoxious and guaranteed to give you a bass headache within 5 minutes of putting them on your head. In addition, the over-sized bass intrudes heavily into the lower midrange, muddying the sound considerably.

This overwhelming bass force causes the whole flimsy assembly of these headphones vibrate, shake, rattle and roll all over your skull. One thing no amount of mods will fix is the disappointing build quality of these $450 headphones. When you take them apart during this mod, you will see for yourself what I mean. On the positive side, you can afford 8 AH-D5000s for the cost of one Sony R10. I myself plan to eventually own 2 of them, an "heir and a spare", as the English say, just in case.

Another major problem with the D5000 is the ultra-thin cushions within the ear pads which insure that the drivers are practically sitting right on top of your ear drums. This made them somewhat obnoxious and overblown, creating a "wall of sound", where everything comes at you at once. You want to duck behind your comfy chair to get away. Also, one thing the Sony R10 and the JVC-DX1000 (two of the soundstaging champs of all time, IMO) have taught me, is that one of the keys to obtaining a proper soundstage is to simply move the driver away from the ear. Both those cans have a lot of space between your ears and the driver, and this allows the soundstage to expand left and right and lends the image a sense of depth and layering. Moving the driver away can also reduce the feeling of air being pushed against the ear drum which tends to localize the sound inside the ear cups. With a driver so close, it's constantly calling unnecessary attention to itself by pumping and vibrating. It can spoil the illusion of a soundstage outside your head, always reminding you that you are actually listening to two tiny speakers strapped to your ears.

Nevertheless, I could still hear there was an incredible amount of potential in these cans. It occurred to me that the main source of the issues was not the D5000’s drivers, but rather the flimsy and borderline pathetic construction of the rest of the headphone. There is no damping of vibration whatsoever. If you could start to eliminate the added vibrations, you could go a long way toward correcting the problem. Hmmmmm…

Advantages Of This Mod Over Stock:
--Remarkable tightening of bass response, to the point it actually sounds coherent and no longer intrudes into the rest of the sound.

--The tightening of bass allows the previously recessed mids and highs to bloom a little more, improving resolution, and restoring balance to the frequency response. But don't panic! You lose none of the Denon's remarkable bass depth, it will still plumb the nether regions like no other phone. You are only removing the extra false resonances of the assembly and ear cups. This is not real bass information.

--Removal of most of the vibration in the assembly, which yields a much less “farty” bass sound and less blurry image. Your mind's eye is now free to wander the soundstage/headstage as your brain is not being reminded of the twin little drivers vibrating away on your skull. No more bass headaches!

--Midrange allowed to bloom and come forward with the lower midrange no longer muddied by overwhelming bass.

--Thanks to the mods to the pads, you get a bigger soundstage left-to-right and up and down, plus signicantly greater soundstage depth.

--Partial closure of the gap in the center of the image.

--Blacker background.

--Slightly improved isolation.

Consequences Of The Mod
--In the process, you will probably rub off the stenciled lettering on the outside of the ear cups, an already noted problem with the Denons. Oh well!

--You've got to be very careful with the teeny tiny screws. Try to avoid multiple screwing and unscrewing of them; you may find they start to become loose over progressive tamperings.

--1 bag of Mountain Mist Fiberloft Polyester Fiberfill. Alleged to have superior acoustic properties than cotton or other forms of polyester filling. Available at your local hobby/crafts/fabric store. $7.

--1 bag of disposable plastic cups with a 3" diameter. Available at your grocery store. $3.

Tools You Will Need
--1 small Phillips head screwdriver, of the kind that typically come in a kit to repair glasses.

--I pair of scissors.

--1 hole punch(er)

--------------------------Procedure--------------------------

Step 1: The "Taper Mod"-- Stuff the Ear Pads With Fiberloft
--Place the flat of your palms firmly up against the ear pad, and applying even, firm pressure, twist the pad counter-clockwise. It will pop out of the assembly.

--You will notice on the underside of the ear pads, there is a little white plastic ring that has notches in it that re-attach the pad to the headphone assembly.

--You will also notice that there is no direct way to access inside the pad where the existing padding is; it's been sewn shut. No problem.

--Take a decent hunk Fiberloft and pull it gently into a longer strip. Roll it between your palms. Take the strip of Fiberloft and stuff it up under the plastic ring into the space between the ring and the existing padding. You will be surprised how much space will open up in there and how much extra material you can get in there.

--At the rear of the pad (the "fatter" end), continue to stuff as much Fiberloft as you can all along the outside edge under the plastic ring; you will need to kneed it and keep pushing it in with your fingers, and eventually you can get a fairly dense and thick layer of material in there.

-- Once you reach the front of the pad (the thinner section), you will want to slowly reduce the amount of Fiberloft you are stuffing under the plastic ring, so it "tapers" gently down until you have a very thin layer of extra padding added to the front vs. the rear which will have as much Fiberloft as you can manage to get in there.

--Why taper it? This causes the drivers to angle slightly away from the ear like the Sony R10 and better Audio-Technicas. This puts the plane of the drivers more in front of your ears and creates a more coherent and seamless soundstage left-to-right. Now sounds seem to come from in front of you as with speakers, rather than having the musicians directly on the left and right hand sides of your head. It also helps move the left and right images closer together in the middle, helping to close the center gap in the soundstage most headphones have.

--Here is a pic of a stuffed pad, an unstuffed pad, and the plastic cup you will need shortly:

--Take your 3" Diameter cup (3 inches across at the top open end), and cut a thin ring off the top of the cup. You will need to also taper this ring, having more height in the rear and less in the front like so:

--Now insert the ring inside the ear pad with the outer lip side down against the fabric. The ring is used to contain the Fiberloft and keep it under the pad where you want it:

--Voila! Your ear pad mods are done. To re-attach, just do the opposite of what you did to take them off. They will click into place. But not yet! We need to access to the rest of the headphone assembly.

--The wooden ear cup will come off. Be careful not to lose the tiny screws!

--Take the ear cup and place on top of your sheet of Dynamat. Trace around the outside edge with a pen which will leave a slight depression in the surface of the Dynamat. Cut out this circle:

--Trim a very thin slice off the outer edge of the circle, otherwise, it will be slightly too large to fit inside the earcup.

--Snip out 4 small notches in each of the 4 corners of the circle that correspond to the little protrusions within the earcup that the screws screw into:

--Remove the backing of Dynamat and apply to the interior of the ear cup.

--IMPORTANT TIP-- You must always press hard and really work the Dynamat into place any time you are applying it. Make sure no air is trapped underneath and that every square millimeter of it is sticking hard against the surface it attaches to.

Step 3: Damp The Rear Of The Driver
--Now you are ready for the most crucial step, damping the rear of the driver.

--Please note when looking at the rear of the driver, you will see it is full of holes and covered by a thin membrane of cotton-like fabric. You must not cover any of these holes! Or at the very least, minimize any coverage that will inevitably occur. These holes are crucial to the sound of the headphone, allowing air to pass. Think of the holes as the link to the open space in the rear of a speaker cabinet behind the speaker driver/woofer.

--First, you will be adding Dynamat to the smaller butt-end of the driver assembly. Note there is a hole on the middle of this butt (covered by the thin cotton paper layer).

--Cut two small circles of Dynamat, slightly larger than the size of a quarter:

--Using your hole punch, punch a hole directly in the center of the circle. Now, still using the punch, punch out a slightly larger hole, it will not be big enough after the first punch.

--Now cut a small notch in the outer edge of the circle. This will give you extra room to accommodate the little circuit board where the wires attach to the driver.

--You are now ready to apply this Dynamat circle to the butt of the driver. If you have cut the correct size, the hole will correspond to the hole in the rear of the driver and the outer edges of your circle will just fold over the edges of the driver butt, so the entirety of the driver butt is covered:

--Now cut a long thin strip of Dynamat. This will be used to surround the outer sides of the larger protrusion behind the driver.

--Cut it just thick enough so the outer edges fold over and cover the edges of the black plastic. Be careful not to use too much or you will end up covering the air holes:

-----------------OTIONAL STEP-------------------

I no longer recommend stuffing the cups with fiberloft (Stuffing pads is still strongly recommended)! You can experiment but will find it doesn't always improve everything in all areas.

Step 4: Add Fiberloft To The Earcup
--I am now making this step an optional one. I have done endless A-B-ing of stuffed and unstuffed pairs over many weeks and agonized over this step. There are no free lunches. Stuffing the cups gives you that last bit of bass control the phones need. It also is effective at preventing backwave distortion. OTOH, stuffing the cups also brings the highs forward a bit and tends to emphasize the somewhat sibilant and grainy nature inherent in the D5000s driver. This is a transient effect, subtly audible or noticeable on about 25% of recordings.

--Unstuffing the cups allows the bass to come a bit too far forward on 20% of recordings. However, it also allows the highs to relax and recede a little bit, making any sibilance or brittleness less apparent and smoothing it out on a small scale. Unstuffing the cups has another effect: it adds some reverb and causes the sound of the cups/chamber behind the driver to be subtly heard. This has positive and negative effects. On the plus side, it lends the recordings a greater sense of depth and ambience, darkening the background, as well as giving the midrange a greater sense of body. On the negative side, it can slightly localize sound inside the ear-cups, slightly reducing the "out-of-head" experience.

--So again, no free lunches, and only you can decide which set of pluses and minuses you can live with. Personally, I've decided that I marginally prefer the cups unstuffed and will not be stuffing them anymore as a standard part of the mods I provide. YMMV, and you may well just as easily prefer them stuffed. OK, here are the steps for stuffing the cups:

--This is the most difficult part to illustrate correctly and the easiest to get wrong.

--BEWARE-- You are in DANGER of adding TOO MUCH Fiberloft! Too much will suck all the bass juice out of your headphone and wreck all the hard work you've just done. This step is crucial for dialing the bass response *just right*. You will be tempted to pack it all in there and clamp the earcups closed within a millimeter of their life and barely get the screws in, but that's ALL WRONG!

--Take the amount of Fiberloft you think you will need to fill the basin of the wooden earcup from the bag. Now cut it in half. Take the Fiberloft and pull it apart, you do not want thick, heavy concentrations. Leave the center of your circle of Fiberloft even thinner than the outer edges.

--Unfortunately, this pic is very deceptive. It is a A LOT THINNER in consistency than it looks. You should be able to see through it a bit so you can see the writing on the Dynamat lining the earcup. Basically, you should end up with a layer so pulled apart and thin it could blow away if you breathe on it wrong.

--Carefully replace the earcup with the Fiberloft back on to the assembly.

--Screw the round head scres back in to re-attach the earcup.

--Now we move to the front of the driver assembly and mod-ing the frame itself.

Step 5: Unscrew The Driver Assembly From The Headband Assembly
--You will notice 4 tiny phillips head screws, screwed into the metal.

--Unscrew them and set aside these screws, they are slightly different from the screws in the wood enclosure. They have a flat head, where the ones that go into the wood have a rounded head.

--The wooden ear cup and the driver will detach from the main assembly. Make a mental note of what the holes look like that you just removed these screws from.

--You will notice a foam ring that will likely fall out at this stage. Don't worry, it just sits in there loosely and can be re-seated when you are done mod-ing.

--You are now ready to mod the headphone assembly.

Step 6: Mod/Damp The Metal Headphone Assembly
--This step is the least important of all the steps; if you feel lazy, you may skip this step. However, if you want to perfect the mod, this definitely contributes to the overall good. It helps prevent vibrations in the flimsy metal assembly.

--We will be applying 4 small pieces of Dynamat to the back side of the metal assembly. You may be tempted to apply a layer of Dynamat to the whole thing, but you will find it makes the assembly very heavy (Dynamat is deceptively heavy for its thickness), and cumbersome, and this may create some comfort issues for you down the line.

--Pick 4 corners of the assembly and attach four 3/4" strips of Dynamat:

Step 7: Mod/Damp The Driver Assembly Topside
--Remember that we want to avoid covering any of the holes in the driver assembly to allow proper air flow, so it is not simply a matter of sticking Dynamat on the driver surface willy-nilly.

--Take a piece of paper and use it to cover half of the driver surface. Tape it in place.

--Using a sharpened pencil, use the side of pencil lead and shade carefully and gently to get an impression of the surface.

--Using the wooden cup, again trace around the edge and cut out a circle of Dynamat.

--Cut this circle in half.

--Place the half-circle of Dynamat behind the impression you left on the paper.

--Using a ball-point pen, punch a hole through the paper and into the Dynamt in the center of each hole.

--Remove the paper and now you have a template of Dynamat with little pin-holes to show you where to punch.

--Using your trusty hole puncher, punch out all the holes.

--Line up all the holes on your piece of Dynamat over the holes in the assembly and apply your new piece.

--Repeat for the other half of the driver face. It should look like this when you are done:

--As always make sure to really work the Dynamat into the surface of the driver to make sure you get best seal.

--Now carefully take the earcup/driver assembly and re-attach to the headband assembly. You will see two notches on either side of the wooden cups. These notches correspond with the point at which the headband assembly connects to the earcup/driver assembly.

--You will notice that you may have to tug on the headphone cable to pull the earcup/driver assembly fully into place and prevent the wire from bundling up in the earcup.

--Now you may screw the flat head screws back in.

Final Steps
--Make sure you place the small foam rings back on top of the front of the driver assembly before you re-attach the ear pads.

--Now, re-attach the ear pads by doing the exact opposite of what you did to take them off. When you apply even pressure the little tabs will pop back in to place and when you twist them, they will lock back in. Remember-- the smaller thin part with the seams goes in front, the fat part goes in the rear. For best fit, I suggest you re-attach the ear pads so that seams match up like so against the joint where the headband assembly attached to the earcups/driver:

Burn-In
I've had the fortune of being able to compare 3 Denons head-to-head, with the only difference being the amount of burn-in on them. These cans NEED BURN-IN. If you take them out of the box and perform the mod, you may notice they're a hair muffled and laid back in the upper mids and highs. Don't worry-- this goes away with burn-in. They will open up and bloom like a spring flower, but you have to be patient. Play them 24/7 with your most obnoxious music played at very loud volumes for 200+ hours for best results.

These phones are not "done" until they're FULLY burned in!

Congratulations!
You've now successfully completed mod-ing your Denons. Again, it is only after an insanely painstaking process that only a headphone loon like me would engage in that I finalized this mod. I am confident that if you follow these instructions carefully, you will cure the Denon of all of its ills, and dial in the bass response as perfectly as humanly possible.

You will end up with a headphone that should have the capacity to amaze and delight you. It has the most natural tonality of headphone I've ever heard, and sounds more realistic and more like life than I ever thought a headphone could. It has more pure resolution and fine detailing than even my beloved Sony R10s. The soundstage is wide and engulfing, with almost the same pinpoint accuracy of the Sony. The Denon clobbers the Sony in terms of bass depth and punch, yet the mods prevent the headphone from overwhelming the listener with flabby flatulent, punishing bass like the stock phone. I will stop describing the positives of the mod-ed Denon here so you can go on to discover them for yourself. All I can say is that they've taken my musical enjoyment to a whole new level, and I hope they will do the same for you.

Post-Script: I'm Scared Of Doing The Full Mods. What If I Only Want A Little Bass Tightening?
I recognize there are folks here who think there's absolutely nothing wrong with the stock Denon D5000. Obviously, for those people, there would be no point in doing these mods. Better to leave well enough alone. There will always be people who like the sound of 12 subwoofers in the trunk, and that's fine.

However, if your impressions of the stock D5000 match mine, then you owe it to yourself to give these mods a try in full.

But what about the guy in the middle? You don't care about the bass bloat of the Denon's quite as much as I do, but you wouldn't mind a little tightening up. For you, I would suggest the following:

1. Do the ear pad taper mod. This should be mandatory no matter what. It is totally reversible if you don't like it.
2. Apply the circle of Dynamat (with center hole) to the smaller butt of the driver.
3. Apply the layer of Dynamat to the inside of the ear cup.

You will end up with a phone that is about half way between the overblown stock phone and the "perfectly balanced" full set of mods. It will still rattle your skull a bit, but you will experience a very solid degree of tightening. From this point, you can do some more critical listening and decide for yourself if you want to go any further or not.

Is It Possible...

Would it be possible/practical to spray the outside of each wooden cup with clear laquer to seal the printing and prevent it from wearing off? Or maybe seal just the printing with clear nail polish, or something?

I suppose that would require a pretty "deft hand" to do it without ruining the finish (lint free, bubble free, wave free, etc.).

Would it be possible/practical to spray the outside of each wooden cup with clear laquer to seal the printing and prevent it from wearing off? Or maybe seal just the printing with clear nail polish, or something?

I suppose that would require a pretty "deft hand" to do it without ruining the finish (lint free, bubble free, wave free, etc.).

It seems like the JVC engineers are 'ruining' their headphones on purpose to cater to the masses.. Ala, flabby, farty bass.. & Why aren't the engineers doing what Mark did? Maybe he should work on the successor.. He seems to be the only one that knows what they are doing. Most of that DIY is above me. But I'd have no problem paying someone to do it for me..

ecclesand,
I don't intend at this time to go into any business mod-ing these headphones. Frankly, I'm sick and tired of the whole process! It takes time and patience, I won't deny that, but I'm not some noted electrical engineer or even a DIY builder of headphone amps. I'm just a dedicated layman, and I feel anyone could pretty easily do this, so long as they are patient.

That's why I wanted to share it with everyone so they could do it themselves.